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Turbo O2 sensor?


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I have a spare MAF laying around so I decided to open it up and see where exactly those traces where and solder in a variable resistor. But guess what?

My MAF is totally different :mad:

I will try to take a picture later on, but my cell phone is acting up (windows mobile :rolleyes:) and my normal camera is empty...

 

Well all is not lost, I'm sure there is some way to mod it. Take some detailed pics, maybe I can see something?

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Hey presslab,

 

I'm glad to hear that you are recuperating so well and that you're back up and about. Oh yeah, and Thank You for your willingness to help. I really appreciate it. I like the modded TD04 you have. I am going to try and look for one sometime in the near future as I have heard lots of good things about performing this mod. I am going to try and locate one locally(here in Okinawa) since they already have the 90* bend at the intake. I'm sure that someone has one. If not, I'll just get a USDM one.

 

Patrick

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Is the JDM one with the elbow still a TD04?

 

I am still waiting for my downpipe to arrive, I should get it on Thursday. Hopefully it won't need too much modding; I do expect to add the o2 bung, I bought an anti-foul spark plug spacer (M18x1.5) and cut the end off.

 

I'm also waiting for an oil drain hose, I'll post some more pics soon when I have the turbo bolted down.

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Is the JDM one with the elbow still a TD04?

 

Yeah, they only came on JDM WRX GF8 wagons and automatic GC8 sedans. With so many people upgrading and junking Subarus over here, I'm sure that I can snatch one up without paying alot of money, well, hopefully.

 

BTW, the engine is looking good!

 

Patrick

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Received the downpipe/midpipe today, it practially bolted on like it was stock! :banana: I added the o2 bung, and I needed to bend a few things to get some clearance. The support bolt at the transaxle front bolted up fine, and so did the hanger at the transaxle rear.

 

The clearance between the propshaft and the end of the midpipe is pretty minimal; it clunks when I go in reverse. I am going to heat the midpipe with a torch and bend it a bit.

 

I still need to do the catback exhaust... I was planning on just hooking to the stock pipe but it's all rusted anyways and pretty small at 1.75". I'm going to do 2.5" and some turbo muffler.

 

IMG_1739_Small_.JPG

 

 

IMG_1744_Small_.JPG

 

 

I drove it around with just the two cats, it's loud but not super loud. It was 98F today and normally the car is dog slow with that much heat. The VF7 is pretty much just blowing hot air at 11 PSI and the timing gets pulled way back. But with the TD04 it still had decent power. This was my primary motivation for the TD04, to get decent power when it is hot out.

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That's awesome! I'm glad that everything is working well. I'm interested, what kind of boost are you running with that TD04 and what kind of intercooler are you running?

 

I know with my current setup(VF7 and Starion intercooler), I am running at the max(11psi via a manual boost controller), but even on a hot day in Texas, the IC would be at ambient temperature, if not a little colder after driving, well, at least the last time I drove it. :(

 

Patrick

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That's awesome! I'm glad that everything is working well. I'm interested, what kind of boost are you running with that TD04 and what kind of intercooler are you running?

 

I know with my current setup(VF7 and Starion intercooler), I am running at the max(11psi via a manual boost controller), but even on a hot day in Texas, the IC would be at ambient temperature, if not a little colder after driving, well, at least the last time I drove it. :(

 

Patrick

 

I am also running 11 PSI. The intercooler is a stock WRX one.

 

I need to work on an intercooler shroud to the hood, I also just received a stock WRX "splitter" that I will modify. The intercooler is cold after freeway driving but after being in traffic it does get quite warm. A better intercooler setup would improve slow speed power and sustained power, but I believe the problem I had with the VF7 was that it just wasn't efficient at 11 PSI; basically just blowing hot air.

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  • 2 weeks later...
The intercooler is cold after freeway driving but after being in traffic it does get quite warm. A better intercooler setup would improve slow speed power and sustained power, but I believe the problem I had with the VF7 was that it just wasn't efficient at 11 PSI; basically just blowing hot air.

 

Mine actually stays cold even with just leisurely driving speeds. I was really, and pleasantly surprised. I know what you mean about the VF7 being inefficient at 11psi. I was told by some of the members here on the forum about that when I first began to mod my car. I have polished the inside of the compressor housing(to a light mirror finish) and I bored out the wastegate port to keep boost creep to a minimum. I really would like to get the exhaust snail polished out though. Another thing that I had done was a custom bellmouth downpipe. I will more than likely play around with it some more and see how much more I can squeeze out of it before I install a TD04.

 

Patrick

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Well it's finished, the TD04 is installed using WRX downpipe w/ cats and custom 3" catback exhaust. It's sweet! :banana: The topend pulls all the way to redline with no hesitation and it doesn't seem to have any issues with hot weather. I tested upping the boost to 14 PSI and it really had no issues, did not go lean, and had lots of power. Right now it's back to 11 PSI.

 

The boost pressure does not seem as stable as before, something to do with the 3 port stock boost control solenoid. There is a restrictor in there, perhaps I need to modify that.

 

The exhaust has a 3" Thrush muffler, it's like a knockoff flowmaster I guess. It has a nice deep rumble at idle but it's a bit too loud for my taste. I like the tone though, so I plan on adding a glasspack to quiet it down.

 

These are the parts I bought from Jegs.com, about $111 shipped for the exhaust as it is now. The Mustang ball flange fit the WRX downpipe great.

 

289-17657 MUFFLER WELDED 3.0" O/C 29.99

289-31896 FLANGE MUSTANG TLP 11.99

289-42323 MANDREL U BEND 3" OD 22.99

555-30611 EXH TUBING 3.0"X4'(EA) 16.99

555-30611 EXH TUBING 3.0"X4'(EA) 16.99

 

 

I'd post some pics but looks like the photo gallery is not working now.

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Not very exciting but here is one pic:

attachment.php?attachmentid=5917&stc=1&d=1221599293

 

I cut off, bent, and welded the original hangers. The muffler is a offset input center output. I plan to put a small glasspack on the tailpipe section, as adding it to the center section would further reduce ground clearance. I left a finger-width clearance from the body and propshaft, and the midpipe is higher than the cat and diff but not by much.

post-9154-136027629447_thumb.jpg

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SO the car hits fuel cut when the maf gets maxed out? I thought it was a pressure switch that cut it. I dont mean to hijack the thread.

 

The "4 plug" ECUs, like mine, use a hot-wire MAF sensor. These models do not have a pressure switch connected to the ECU like the "3 plug" ones do. The ECU will fuel cut when the MAF reading gets to a certain voltage; the fuel cut is a safety for the turbo system, if the wastegate fails closed and the engine flows too much air, the ECU will cut fuel to the engine.

 

With the larger injectors the engine is supplied more fuel for the same MAF reading. By adjusting the MAF and lowering the voltage it can compensate for the larger injectors. The advantage of this is two-fold: The engine can supply more fuel so it does not go lean at high boost levels, and the MAF voltage is lowered so it will fuel cut at a higher boost.

 

http://www.ausubaru.com/forum/showthread.php?t=3784

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I just installed a short 12" Cherry Bomb glasspack, right after the muffler before the exhaust tip. Perfect - it is still nice when I get on the gas but now it's much quieter in the car while cruising.

 

 

About the fuel cut - make sure that you do not run lean!! If you up the boost it needs more fuel, and at a certain point the stock system can not keep up. If you up the boost and run lean you will grenade your engine.

 

It is possible to delay the onset of fuel cut with the hot-wire MAF system too! With only the adjustment mod on the MAF, adjust the pot 'lean' so the computer thinks there is less air. The o2 sensor will allow the long-term-fuel-trim to adjust for the MAF error, but the fuel cut will come on at higher air flow.

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